Recently, miniaturization of semiconductor production techniques has increasingly progressed, in such a way that the state-of-the-art process has adopted generations having wiring widths of the order of 20 nm and further 10 nm. Miniaturization goes with the enhancement of the technical difficulty in the miniaturization processing, and technical developments have been progressed from various aspects of approach, with respect to the materials, apparatuses, processing methods and others to be used.
Under such circumstances, the present applicant has also developed a dry etching gas capable of coping with the state-of-the-art dry etching process, and has discovered that saturated fluorinated hydrocarbons having small number of fluorine atoms such as 2-fluorobutane have performances surpassing monofluoromethane being used in etching of silicon nitride films (Patent Literature 1).
Several methods for producing 2-fluorobutane have hitherto been known. For example, Patent Literature 2 describes a production of 2-fluorobutane in a yield of 46%, by bringing N,N′-diethyl-3-oxo-methyltrifluoropropylamine as a fluorinating agent into contact with 2-butanol. Patent Literature 3 discloses that the production of fluorinated sec-butyl was confirmed by bringing sulfur hexafluoride into contact with a sec-butyllithium solution in a cyclohexane/n-hexane mixed solvent. Patent Literature 4 describes the preparation of 2-fluorobutane by hydrogenation of 2-fluorobutadiene in the presence of a catalyst. Non Patent Literature 1 also discloses a method for preparing monofluorinated hydrocarbons by acting acetyl fluoride as a fluorinating agent to ether compounds having a cyclic structure such as adamantyl methyl ether and cyclohexyl methyl ether in the presence of a catalyst such as boron trifluoride phosphoric acid complex or zinc fluoride.